Cleaner production of ephedrine from Ephedra sinica Stapf by membrane separation technology

A promising cleaner approach, including chemical extraction, separation and purification by membranes separation technology, for producing ephedrine from Ephedra sinica Stapf was introduced. The extraction yield of ephedrine reached 92.45 ± 0.46%, increased by 28.25 ± 0.13% than that of the traditional process, at solid-to-liquid ratio of 1/10, extraction temperature of 80 °C, total extraction time of 20 h and reextraction for 3 times. In microfiltration, the transmissivity for ephedrine was up to 97.88 ± 1.06% and the retention rate of impurities reached 78.56 ± 0.96% when the membranes with pore size of 0.45 μm were employed at inlet and outlet operating pressure of 0.26 MPa and 0.14 MPa, respectively. The surface velocity of membrane channel was 3.5 m s⁻¹ and membrane flux was 207 ± 3.71 l m⁻² h⁻¹. Nanofiltration membranes with 160 Da molecular weight cut-off (MWCO) were adopted to separate the ephedrine from microfiltration permeate at a transmembrane pressure of 0.6 MPa wherein the retention rate of ephedrine reached 99.88 ± 0.23% and the membrane flux was 19.88 ± 1.12 l m⁻² h⁻¹. For this improved approach, the COD of nanofiltration permeate was only 110 ± 12.56 mg l⁻¹ which could be recycled to the extraction process, causing a decrease by 59.38 ± 1.67% of water consumption and 75.76 ± 1.89% of wastewater generation in comparison with those of the traditional process.